As a means for percutaneously administering an agent, a microneedle device is known. In some of such devices, a coating containing a drug and a thickener is formed (for example, Patent Literature 1).
In addition, a composition including a preparation composed of a biologically active substance and a viscosity-enhancing counterion (Patent Literature 2) and a coating formulation having a pH less than about 6 and containing at least one low-volatile counterion (Patent Literature 3) are known. Furthermore, a composition including a preparation composed of a therapeutically effective amount of a peptide agent and at least one counterion (Patent Literature 4) and a composition including a preparation composed of a biologically active ingredient and non-volatile counterion, having enhanced pH stability and solubility when dried (Patent Literature 5) are known. There is, in addition to these compositions, a coating containing a biological active substance and an additive, where a low content of an amino acid is used as an example of the additive (Patent Literature 6).